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双相不锈钢堆焊层应力腐蚀性能评价

Evaluation of stress corrosion of duplex stainless steel overlay

  • 摘要: 为防止换热器等设备发生应力腐蚀,工程上试采用在与腐蚀介质接触的表面堆焊2205双相不锈钢.为探索方案的应用范畴与可行性,对两种焊接工艺(自动焊及焊条电弧焊)、3种工程上常见腐蚀环境(饱和硫化氢、氯化镁、氯化钙),通过恒负荷拉伸试验方法及断口微观分析手段,综合评价其应力腐蚀性能,并根据试验结果建立应力—寿命数学模型.结果表明,饱和H2S环境中恒负荷拉伸门槛值σth自动焊为0.45ReL、焊条电弧焊为0.4ReL,二者相差17%.氯化钙环境中0.9ReL应力下96 h试验后所有试样完好,显示出优良的抗氯化钙应力腐蚀能力.而该材料则不适于在沸腾氯化镁环境下工作.

     

    Abstract: In order to prevent stress corrosion in petrochemical facilities,2205 duplex stainless steel was deposited on the surface contacted with the corrosive media in projects. In order to explore the application scope and feasibility of the solution, two welding processes (automatic welding and manual welding),three kinds of common corrosion environment (saturated hydrogen sulfide,magnesium chloride,calcium chloride) were used to evaluate its stress corrosion comprehensively at the constant tensile load based on the microanalysis of fracture,and the mathematical model of stress-life was established based on the experimental results. The results indicate that the constant tensile load threshold is 0.45 ReL for automatic welding and 0.4 ReL for manual welding in saturated H2S environment,and there is an error of 17% between them. All the samples are good after 96 hours in 0.9 ReL stress test with the calcium chloride environment, which shows the excellent resistance to chloride stress corrosion. But the coating cannot be used in boiling magnesium chloride environment.

     

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